Method for making sym-tris(4-pyridyl) cyclohexanes and alkyl substituted sym-tris (4-pyridyl) cyclohexanes



United States Patent 01 hce 3,528,988 Patented Sept. 15, 1970 3,528,988METHOD FOR MAKING SYM-TRlS(4-PYRIDYL) CYCLOHEXANES AND ALKYL SUBSTITUTEDSYM-TRIS (4-PYRIDYL) CYCLOI-HEXANES Heinz, Uelzmann, Cuyahoga Falls,Ohio, assignor to The General Tire & Rubber Company, a corporation ofOhio No Drawing. Continuation-impart of applications Ser. No. 507,556,Nov. 12, 1965, and Ser. No. 571,687, Aug. 11, 1966. This applicationOct. 12, 1967, Ser. No. 674,760

Int. Cl. C07d 31/42 US. Cl. 260296 10 Claims ABSTRACT OF THE DISCLOSURE4-vinyl pyridines are trimerized in the presence of an alkali metalorganic imide in a solvent, for example the reaction product of sodiumand ethylenimine in the presence of excess ethylenimine, to form1,3,5-tris(4pyridyl) cyclohexanes which can be reacted with alkylbenzene sulfonic acids to make oil soluble wetting agents useful 1nmaking water-in-oil emulsions. The 1,3,5-tris(4-pyridyl) cyclohexanescan also be hydrogenated to form 1,3,5- tris(4 piperidyl) cyclohexanes.Both types of cyclohexanes find utility as accelerators for sulfurcurable millable rubbers and resins, for example, natural rubber. The1,3,5-tris(4-piperidyl) cyclohexanes can be used to cure epoxides, oranhydride containing polymeric materials (for instance, the copolymer ofmaleic anhydride and styrene); they will also crosslink or chain extendisocyanate terminated polyurethane prepolymers, or polyisocyanates, andcan be used in the one-shot processes of making polyurethanes by mixingwith the polyol, H O, etc. The 1,3,5-tris(4-piperidyl)cyclohexanes canbe reacted With epoxides and/or episulfides to make ethers and/ orthioethers and polyether and/ or thioether polyols and/or polythiolswhich can be reacted with isocyanates or polyisocyanates to makepolyurethanes and polythiourethanes.

This application is a continuation-in-part of prior patent applicationsS.N. 507,556, filed Nov. 12, 1965, and entitled Method For Producing1,3,5-Tris-4-Pyridylcyclohexane and SN. 571,687 filed Aug. 11, 1966 andentitled Tris(4-Pyridyl) Cyclohexanes, Method For Making The Same, TheCorresponding 4-Piperidyl Compounds and Their Use With Epoxides, bothnow abancloned.

This invention relates to a process for producing 1,3,5- tris(4-pyridyl)cyclohexanes and to the products of said process. More particularly,this invention relates to a process of trimerizing 4-vinylpyridine toproduce 1,3,5- tris(4-pyridyl) cyclohexane. It, also, relates to theproduction of the corresponding 4-piperidyl type compounds and their usewith epoxides and other reactants and so forth.

Heretofore, 1,3,5 tris(4 pyridyl) cyclohexane has been produced in verysmall yields by the pyrolysis of polymeric 4-vinylpyridine.

It is an object of this invention to produce 1,3,5-tris (4-pyridyl)cyclohexanes in yields higher than have heretofore been possible with aconsequent reduction or elimination of by-products including polymers.Another object is to produce compounds of the 1,3,5-tris(4-pyridyl)cyclohexane type. A further object is to provide the corresponding4-piperidyl type compounds. Still further objects are to provide novelcuring, cross-linking, chain extending agents as well as accelerators.These and other objects and advantages of the present invention will become more apparent to those skilled in the art from the followingdetailed description and examples.

In accordance with this invention, 1,3,5-tris(4-pyridyl) cyclohexanesare produced by trimerizing 4-vinylpyridines employing a solvent for the4-vinylpyridines in the presence of a catalytic amount of an alkalimetal organic imide. The solvent, which can also be considered as adispersant or function in part as a dispersant, is the secondary aminefrom which the alkali metal organic imide is prepared and which ispreferred, or other secondary amine as defined herein, or mixtures ofsaid amine(s), and of a solvent which is not proton-active, does nototherwise interfere or react with the alkali metal or alkali metalorganic imide, or which does not deactivate the catalyst. Examples ofsolvents for use with said amines are low molecular weight ethers,polyethers, hydrocarbons, thioethers, i.e., dimethyl ether, dibutylether, ethers of ethylene glycol and diethylene glycol, diglyme, glyme,toluene, benzene, hexane, heptane, tetrahydrofuran, diisoamyl sulfide,dibutyl sulfide, quinoline, pyridine, etc.

Details of the process of making 1,3,5-tris(4-pyridyl) cyclohexanesSecondary amines, preferably cyclic, which can be used in the practiceof the present invention include piperidine; morpholine; pyrrolidine;ethylene imine; propylenimine; 2,3 dimethyl ethylenimine; 2 methylpiperazine; 2,6- dimethyl piperazine; 1,2 butylenimine; 1,2 amylenimine;azetidine; diethylamine; dibutylamine; ethyl propylamine; dihexyl amine;2 ethyl piperidine; 3 ethyl piperidine; dioctyl amine; N-butyl aniline;1,10-diazacyclooctadecane; N-phenyl benzylamine; hexamethylenimine;coniine; 2,6 dimethyl morpholine; pyrrole; imidazole; pyrazole;pyrroline; indole; 2,5 dimethyl piperazine; 1 ethyl piperazine;imidazolidine; piperazine; indoline; and the like. Still other secondaryamines can be used such as N-methyl aniline, N-ethyl butylamine, N-ethyl cyclohexylamine, difurfuryl amine, N(fi-ethoxy ethyl)methy1amine,1 methyl piperazine, 1 phenyl piperazine, 2 pipecoline, tetrahydro 1,4thiazine and the like.

Very desirable to use are cyclic secondary amines of the general formula[(CR (X),,]NH where R is selected from the group consisting of hydrogenand alkyl radicals of from 1 to 4 carbon atoms and mixtures thereof,where X is oxygen or sulfur, where m is a number from 2 to 7, where n isO or 1, and when X is 1 there are always at least 3 CR groups present,two of the CR groups being attached through the C atom directly to thenitrogen atom.

These secondary amines have from 2 to 20 carbon atoms and from 1 to 2secondary amino nitrogen atoms. While mixtures of the secondary aminescan be used, it is preferred to use a single secondary amine tofacilitate handling and recovery of the amine and solvent.

The reaction is conducted by forming an admixture of the secondary amineor secondary amine-solvent mixture containing a small amount of alkalimetal organic imide catalyst most of which is in dispersed form in thesolvent. This admixture is stirred and heated and the 4-vinyl-pyridinecompound added. It is preferred that the addition be one incrementallysince the reaction is usually extremely exothermic and the temperaturerises quickly to cause the secondary amine to boil. By the incrementaladdition, the temperature of the reaction is maintained at approximately20 to 70 C., preferably 54 C., when using 4-vinyl-pyridine,ethyleneimine, and sodium or sodium ethylene irnide. As wolud be obviousto one skilled in the art, too fast an addition would cause too violentboiling of the solvent which might lead to an uncontrollable'reaction.All starting materials, solvent, etc., should be of very high purity toget high yields.

In place of 4-vinyl pyridine, other low molecular weight 4-vinylpyridines can be used in the method of the pres ent invention, such as2-methyl-4-vinyl pyridine, 2-etl1yl- 4-vinyl pyridine, 2-butyl-4-vinylpyridine, 2,6-dipropyl-4- vinyl pyridine, 2-isopropyl-6-butyl-4-vinylpyridine, 2- methyl-6-isobutyl-4-vinyl pyridine and the like andmixtures thereof. These compounds have the general formula CH2=CH Nwhere R is selected from the group consisting of hydrogen and an alkylradical of from 1 to 4 carbon atoms of the present invention it ispreferred to employ single 4- vinyl pyridine compounds rather thanmixtures.

The amount of solvent is not narrowly critical and can be from 100 partsby volume of the solvent for each 100 parts by volume of the 4-vinylpyridine compound to 1,000 parts by volume of the solvent to 1 part byvolume of the 4-vinylpyridine, or even higher. Substantial amounts ofsolvent favor trimerization over polymerization.

The amount of alkali metal organic imide employed as a catalyst is notnarrowly critical but a sufficient amount should be present to causetrimerization rather than polymerization. It can range from .05 byWeight based on the weight of the 4-vinylpyridine compound used to 10%by weight based on the Weight of the 4- vinylpyridine compound. Largeramounts can be employed; however, no commensurate advantages areobtained thereby.

The alkali metal organic imide catalyst can be prepared in situ in thesolvent by the reaction of the secondary amine with at least onematerial selected from the group consisting of M and MA where M is analkali metal and A is selected from the group consisting of NH H, and Rwhere R is a saturated hydrocarbon radical of from 1 to 18 carbon atoms.Examples of M and MA are lithium, sodium, potassium, rubidium, cesium,ethyl lithium, n-butyl sodium, n-butyl lithium, methyl potassium, phenylsodium, ethyl potassium, so damide, lithium amide, potassamide, cesiumamide, sodium hydride, lithium hydride, cesium hydride, potassiumhydride, rubidium hydride, and the like and mixtures of the same. On theother hand, the catalyst can be prepared outside the environment of thesolvent and added to the solvent. Of these catalysts, sodium andpotassium and their above compounds are referred.

The temperature at which the trimerization takes place is not narrowlycritical. It can vary from about 20 C. to as high as 300 C., preferablyfrom about 20 to 200 C. However, it is preferred to maintain thetemperature at a point at which the solvent is refluxing (boiling pointof the solvent at a controllable rate. In some instances using certaincatalysts and/or secondary amines it is necessary to increase thetemperature to initiate reaction and/or to obtain satisfactory yields oftrimer and/or to reduce the amount of polymer formation. Thetrimerization of the 4-vinyl pyridine compound can be conducted atatmospheric pressure, super-atmospheric pressure and sub-atmosphericpressure.

Since the reactions involve the use of alkali metals, organo alkalimetallic compounds, etc., the reactions should be conducted under aninert or non-reactive atmosphere or in one free of moisture. Examples ofuseful atmospheres to use are nitrogen, helium, neon, argon, dry air,and the like and mixtures thereof.

The trimerized -vinyl pyridines produced by the method of the presentinvention have the general formula:

R 11 H R R H B it where R is selected from the group consisting ofhydrogen and alkyl radicals of from 1 to carbon atoms, i.e., methyl,ethyl, propyl, butyl, isobutyl, etc. and mixtures thereof. Examples ofsuch compounds are and mixtures thereof.

The 1,3,5-tris(4-pyridyl)cyclohexanes -find utility in the preparationof wetting agents by reaction with alkyl benzene sulfonic acids to formsalts with the same. Thus, for example, for each mole of the1,3,5-tris(4-pyridyl)cyclohexane compound, one can employ l, 2 or 3moles of dodecyl benzene sulfonic acid to yield a wetting agent which isoil soluble to make water-in-oil emulsions. These cyclohexane compoundsalso can be treated by methods known in pyridine chemistry leading tothe introduction of new substituents on the pyridyl rings such as NH NOSO H, acyl, halogen and the like.

The following examples will serve to further illustrate this inventionwith more particularity to those skilled in the art. In the examples,all parts are by weight unless otherwise set forth.

EXAMPLE 1 Into a l-liter, 3-neck flask, fitted with a dropping funnel,reflux condenser, thermometer and stirrer, pure ethylene imine (250grams) and sodium (6 grams) were charged under a nitrogen atmosphere.The mixture was heated to approximately 45 C. for about 20 minutes withstirring. Freshly distilled 4-vinyl pyridine (210 grams) was addeddrop-wise into the vortex of the rapidly stirred mixture. A dark redcolor appeared and the temperature rose to approximately 50 C. rapidly.The rate of addition of 4- vinyl pyridine was controlled so that thereaction temperature was maintained between 50 C. and 54 C. After theaddition of the 4-vinyl pyridine was completed, the reaction mixture wasrefluxed (approximately 54 C.) for 1 additional hour. Then most of theethylene imine was distilled off into a Dean-Stark trap and the reactionmixture cooled. After cooling, cubic centimeters of iso propanol wereadded to the flask with stirring to form sodium isopropoxide and releaseethylene imine by reaction with the sodium ethylene imide, i.e.,

on. Na N omononcrr CH: HN/ otnonomon 7 EXAMPLE 7 To a nitrogen flushed 1liter 3 neck flask were charged I 510 g. of piperidine (redistilled) and6 g. of potassium. The flask and contents were heated (about 105-110 C.)to refluxing for 30 minutes. Then 105 g. of 4-vinyl pyridine were slowlyadded while continuing heating and refluxing. After addition thecontents were stirred for 45 minutes at refluxing temperature. Thetrimerization took place suddenly after 45 minutes of stirring and partof the material boiled out of the flask because of the heat produced.Therefore, part of the product was lost. The remaining material waspoured into 700 cc of demineralized water in a beaker, stirred for -15minutes and then filtered. The precipitate or filter cake(1,3,5-tris(4-pyridyl) cyclohexane) weighed 90 g. (85.7% of theory). Theprecipitate was recrystallized from dimethyl formamide and had a meltingpoint of 225-227 C.

EXAMPLE 8 To a nitrogen flushed 1 liter flask were charged 228 g. (2.62m.) of pure morpholine and 3 g. of potassium. The contents of the flaskwere refluxed for 1 hour at 126 C. Then there were added to the contentsof the flask 46.2 g. (0.44 m.) of 4-vinyl pyridine dropwise so as tomaintain refluxing over 30 minutes. A purple complex was formedimmediately and the reaction was fairly exothermic. After the additionof the 4-vinyl pyridine heat was maintained and the contents of theflask were refluxed for 30 additional minutes. The morpholine wasdistilled from the flask using a Dean-Stark trap; 190 cc. of morpholinewere recovered. Then 25 cc. of (2% C H ethanol were added to the flaskto destroy any unreacted potassium. The contents of the flask were thenpoured into 500 cc. of H 0, and the precipitate obtained was filtered,washed with water and dried. The yield obtained of 1,3,5-tris(4-pyridyl)cyclohexane was 43 g. (93.1% of theory); it had a melting point of224227 C.

EXAMPLE 9 To a nitrogen flushed 500 cc. flask were charged 3 g. ofpotassium and 270 g. (2.09 mols) of dibutyl amine (freshly distilledover sodium). The contents of the flask were heated and refluxed (about158 C.) for 1 hour. Then 42 g. (.39 mole) of 4-vinyl pyridine wereslowly added to the flask while refluxing and over a period of 30minutes. The flask and contents were heated and refluxed while stirringafter addition of the 4-vinyl pyridine.

During the addition of the 4-vinyl pyridine a sticky red complex formedon the potassium. This caused the forma tion of a lump of material. Asthe addition proceeded the lump dissolved and near the end of theaddition again reformed. The dibutylamine was distilled off from theflask using a Dean-Stark trap; then 50 cc. of denurated ethanol wasadded to the flask to destroy any excess potassium. This mixture in theflask was allowed to stand for about 60 hours and then was poured into300 cc. of demineralized water in a beaker, stirred, filtered and dried.The yield of product (1,3,5 tris(4 pyridyl)cyclohexane) was 14 g. (33.3%of theory). A small portion of the above dry product was re-crystallizedfrom dimethyl formamide, washed once with benzene, and dried; it meltedat 221225 C.

Hydrogenation of tris(4-pyridyl)cyclohexanes It has also been found thatthe l,3,5-tris(4-pyridyl) cyclohexanes can be hydrogenated employingRaney nickel, platinum, nickel and kieselguhr, palladium black,palladium deposited on carbon black, copper chromite, etc., as ahydrogenation catalyst with hydrogen under pressure, for example, about1000-10,000 p.s.i.g., and at a sufficient temperature, for example, offrom about 50 to 350 C. in a solvent to produce 1,3,5-tris(4-piperidyl)cyclohexanes which are useful as chemical intermediates. These4-piperidyl cyclohexanes have the general formula 11 R N H n R H Hz H RHHR Roi H2 HN NH where R is selected from the group consisting ofhydrogen and alkyl radicals of from 1 to 4 carbon atoms such as methyl,ethyl, propyl, isopropyl, butyl, etc. and mixtures thereof. Examples ofsuch compounds are EXAMPLE 10 A one-gallon autoclave equipped with astirrer was purged with hydrogen gas at room temperautre and atmosphericpressure. Then there were added to the reactor and mixed together 151grams of 1,3,5-tris(4-pyridyl)cyclohexane, 3 liters of methylcyclohexane, and 15 grams of Raney nickel. The reactor was thenpressurized (2000 4000 p.s.i.g.) with hydrogen. The hydrogenation wasconducted for /z-1 hour at a temperature of about 200 C. until hydrogenuptake was complete. At the end of the reaction, the reactor was cooledand the mixture was poured into a container. After standing for awhilethe solvent containing the hydrogenated trimer (1,3,5-tris(4-piperidyl)cyclohexane) was decanted and filtered through a fabric filterto remove the catalyst and then subjected to continuous distillation toremove the methyl cyclohexane. When the hydrogenated trimer wassubjected to vacuum distillation (200 Cfand 0.2 mm. of Hg), nodistillate came over. The hydrogenated trimer at room temperature wasalmost transparent and felt tacky; it became a liquid when heated to C.It was soluble in isopropanol, methanol, benzene, and ketones.

Analysis gave the following results: percent nitrogen: Found 11;calculated 12.6. Percent NH: Found 13.50, 13.31; calculated 13.53;meq./g. 8.99, 8.87; Molecular weight: Found 350; calculated 333.4 (vaporphase osometry).

Use of tris(4-piperidyl) cyclohexanes as curing agents The1,3,5-tris(4-piperidyl)cyclohexanes are useful as curing agents forepoxide resins. For example, from about /2 to 45 parts by weight of thetris-4-piperidyl cyclohexanes based on parts by weight of the epoxideresin can be used to cure the resin in forming potting compounds; inbinders for laminates for paper; polyester fabrics, glass fiber clothsor products or mixtures thereof; wood sheets; in coatings on metal suchas steel; in adhesive compositions; and so forth. The tris-4-piperidylcyclohexane in finely divided form can readily be dispered throughoutthe epoxide resin or can first be melted or dissolved in solvent andthen blended with the epoxide resin. Curing times and temperatures canbe those customarily employed in the art. Epoxy or epoxide resins andmethods for handling them are disclosed in the book Epoxy Resins by Leeand Neville, McGraw-Hill Book Co., Inc., New York, 1957, 297 pages.Mixtures of epoxide resins and mixtures of the tris-4-piperidylcyclohexane compounds can be used. Of course, if desired, other knownThe resulting mixture was then transferred into a beaker, and the flaskwashed with isopropanol (400 ml.) which was also added to the contentsof the beaker. The beaker was then heated on a hot plate in a hood withgood ventilation to distill 01f the remaining ethylene imine. Featuresof this process are that part of the solvent is used to form thecatalyst and that the solvent can be completely or almost completelyrecovered for further use.

The mixture was then cooled yielding a crystalline precipitate. Thiscrystalline precipitate was filtered, washed with water, and dried at 40C. and at about 20 mm. of mercury. This crystalline precipitate Weighed184 grams which is 89% of theory based on the starting 4-vinyl pyridine.The crystalline material was recrystallized from methyl ethyl ketone toyield 1,3,5-tris(4-pyridyl)cyclohexane having a melting point of 227229C. It was also recrystallized from dimethyl formamide as well as fromdimethyl acetamide.

Analysis of the 1,3,5-tris(4-pyridyl)cyclohexane gave the followingresults.

Molecular weight: Found 310. Calculated 315. Nitrogen: Found 13.06%.Calculated 13.3%. Carbon: Found 79.24%. Calculated 80.0%.

Hydrogen: Found 6.70%. Calculated 6.72%.

Infrared analysis showed the trimer obtained was identical with theproduct isolated from the pyrolized poly-4- vinyl pyridine as describedin Tetrahedron Letters, No. 17, pages 998-1004 (1964).

When the above example was repeated but the solvent was a mixture of 90parts by volume of ethylene imine and parts by volume of glyme (ethyleneglycol dimethylether) similar results were obtained. The use of4-isopropenyl pyridine, 3-vinyl pyridine or 2-vinyl pyridine in place of4-vinyl pyridine did not provide a trimer using the present process.

EXAMPLE 2 The method of this example was similar to that of Example 1,above. To a 250 cc. nitrogen flushed flask were charged 125 g. ofethylenimine and 3 g. of potassium. The flask and contents were heatedto 45 C., and then there was slowly added 105 g. of 4-vinyl pyridine.The mixture was then distilled using a Dean-Stark trap to remove theexcess ethylenimine. The distilled mixture next was cooled and pouredinto a large volume of water and methanol (5:1 volume ratio) where thecrystals of trimer separated from the oily polymer obtained. Filtrationof the water-methanol mixture using a fritted glass filter followed. Thecrystals or precipitate of the trimer Were washed and dried. A yield of22 grams (21% theory) of 1,3,5-tris(4-pyridyl)cyclohexane was obtained.

EXAMPLE 3 The method of this example was similar to that of Examples 1and 2, supra. Into a 250 ml. nitrogen flushed flask were charged 125 g.of ethylenimine and 3 g. of potassium (freshly cut). The flask andcontents were heated to 45 C. and the dropwise addition of 53 g. (0.5m.) of 4-vinyl pyridine was begun as soon as a blue complex was formedon the K, keeping the temperature between 51 and 54 C. After theaddition the mixture was refluxed for 1 hour. The mixture was thencooled, and the ethylenimine was distilled out. The reaction product wasprecipitated with 3 liters of cold water and filtered. The trimerizationproduct was soluble in methanol. The precipitate obtained was dried andit weighed 36 g. (67.9% of theory). After recrystallization fromdimethyl formamide the precipitate (1,3,5-tris-(4-pyridyl)cyclohexane)had a M.P. of 226-228 C.

This example shows that by increasing the temperature only 69 C. and byusing a more dilute reaction mixture, the yield of trimer obtained isover 3 times that of Example 2, above.

6 EXAMPLE 4 Into a nitrogen flushed 1 liter 3 neck flask were charged342 g. (6 m.) of propylenimine, freshly distilled without inhibtor, and6 g. of sodium, freshly cut. The flask and contents were refluxed for 2hours at about 65 C. 4-vinyl pyridine was added slowly at 58 C. withoutany reaction; approximately 20 cc. additional of 4-vinyl pyridine wereadded without any reaction. The addition was stopped as the flask hadcooled and heat was applied to the mixture until it began refluxingagain. As the mixture refluxed, a slight pink color formed, thensuddenly the reaction mixture began forming a very dark red color andthe addition was resumed at a rate that kept the pyropyleniminerefluxing. The addition time was 20 minutes, and the total amount of4-vinyl pyridine added was g. The mixture in the flask was refluxed anadditional 50 minutes at 66 C. A Dean-Stark trap was connected and theexcess (250 cc.) propylenimine was distilled off. 50 cc. of ethanol(denatured, contained 2% benzene) were added to the flask to destroy anysodium metal remaining and this resulting mixture was added to 500 cc.of demineralized water in a beaker. The flask was rinsed with 200 cc.more of demineralized water. The contents of the beaker were stirred andallowed to stand for /2 hour and filtered. The product,1,3,5-tris(4-pyridyl)cyclohexane, obtained amounted to 61 g. (58.1%yield of theory). The product was re-crystallized from dimethylformamide, washed with pure benzene and dried. Its melting point was222226 C. If the secondary amine and sodium have not reactedsufliciently to form an alkali metal organic imide catalyst insufiicient amounts, polymerization will dominate rather thantrimerization, or the entire product will be a polymer. It is known thatvinyl pyridines are somewhat unstable and undergo selfpolymerization.

EXAMPLE 5 The method of this example was similar to the methods ofExamples 1 to 4, above. Into a nitrogen flushed 1 liter flask werecharged 342 g. (6 m.) of propylenimine (freshly distilled from bariumoxide) and 6 g. of potassium (freshly cut). The flask and contents wererefluxed for 40 minutes. There were next added 105 g. 4-vinyl pyridineat 64 C. with immediate reaction and a color (dark red) changeoccurring. The addition rate was adjusted to keep the propylenimine justrefluxing, and the addition time was 20 minutes. A Dean-Stark trap wasconnected and the excess (281 cc. propylenimine) was stripped out. Next,50 cc. of denatured ethanol were added and the contents were stirred for30 minutes. The resulting mixture was poured into 500 cc. of colddemineralized water in a beaker. After /2 hour the material in thebeaker was filtered and the precipitate obtained was dried. The yieldwas 34 g. (32.4% of theory). The product,1,3,5-tris(4-pyridyl)cyclohexane, had a melting point of 224227 C.

EXAMPLE 6 To a nitrogen flushed 1 liter flask were charged 213 g. ofpyrrolidine and 3 g. of potassium. The flask and contents were heatedand refluxed (about 8895 C.) for 30 minutes. Then over a period of 30minutes 52.5 g. of 4-vinyl pyridine were added while refluxing. Theflask and contents were heated for another 30 minutes under refluxingconditions when 25 cc. of (2% C H ethanol were added and the excesspyrrolidine was distilled off using a Dean-Stark trap. The contentsremaining in the flask were poured into a beaker containing 400 cc. ofdemineralized water. Following this, the contents of the beaker werefiltered and the precipitate obtained was dried to yield 44 g. (83.8% oftheory) 1,3,5-tris(4-pyridyl) cyclohexane. The product wasre-crystallized in dimethyl formamide, filtered, washed twice with purebenzene and dried to give a melting point of 226228 C.

16 grams of Epon 828 and 4 g. of 1,3,5-tris(4-piperidyl) cyclohexanewere mixed together in a beaker at 80 C. and allowed to cool. After 10minutes cooling, the mixture was thick; after 20 minutes, it had becomea thick paste. After 30 minutes the mixture had become a tough paste;and after 1 hour, it had cured to a non-tacky solid which could bedented.

16 grams of Epon 828 and 4 g. of 1,3,5-tris(4-piperidyl) cyclohexanewere mixed together in a beaker at 80 C. After cooling for ten minutes,a thick paste had formed, and the mixture was then placed in an oven at80 C. for 10 minutes. On removal from the oven and cooling to roomtemperature, a hard solid block was obtained which could not be dented.

18 grams of Epon 828 and 2 g. of 1,3,5-tris(4-piperidyl) cyclohexanewere mixed in a beaker at 80 C. and then allowed to cool. After 13 hoursa non-tacky solid was obtained which could be dented.

All of the above cured epoxide resins were dark bluegreen. Epon 828 is abisphenol A-epichlorohydrin type epoxy resin which is a liquid at roomtemperature, has a Gardner color at 25 C. of 12 (max.) and has anepoxide equivalent of 175-210, an average molecular weight of 350-400and a viscosity at 25 C. of 5000- 15,000 centipoises.

The 1,3,5-tris(4-piperidyl)cyclohexanes may also be re acted with acylhalides RCOX, i.e., RCOCl, where R is methyl, ethyl, or other activehydrogen free organic group, to produce amides, or also polyamides andwith isocyanates or multiisocyanates to make ureas and polyureas and tocrosslink and/or chain extend isocyanate containing polyurethanes suchas isocyanate containing -polyesterurethanes, -polyetherurethanes,-polyetheresterurethane, -polyamides, etc. Sufiicient amounts of thepiperidyl cyclohexanes are used to obtain the desired degree of chainextension and/ or crosslinking.

Instead of reacting the sym-tris-piperidyl cyclohexane with anisocyanate terminated prepolymer or with a polyisocyanate, it can bemixed with the ingredients forming the polyurethane such as the polyol(polyether, polyester and/ or polyether-ester or grafted polyols, i.e.,where vinyl chloride or acrylonitrile, etc. has been graft polymerizedon the polyol backbone), catalyst if any or blowing agent and reactedtogether essentially at the same time with the polyisocyanate to formthe polyurethane. A suflicient, usually a minor amount by weight of thecyclohexane as compared to the total weight of the polymer, is used toat least in part crosslink and/or chain extend the urethane polymericunits as they are formed. The resulting polyurethanes can be rigid orflexible, porous or non-porous depending on the selection of polyols,polyisocyanates, blowing agent, etc. and the amount of the cyclohexanecompound used.

EXAMPLE 12 255 grams (.6 mole) of PPG-425 (a polypropylene ether glycolhaving a molecular weight of about 425) was reacted with 208.8 g. (1.2moles) of tolylene diisocyanate (a mixture of 80% 2,4- and 20%2,6-isomers) and slowly heated to 150 C. Then it was allowed to cool andwas stored under a nitrogen atmosphere. The polyetherurethane prepolymerwas isocyanate terminated, was very viscous (barely flowed) at roomtemperature (about 25 C.) and was a liquid at 80 C. 3

The 1,3,5 tris (4 piperidyl)cyclohexane was liquefied at 80 C. and 1gram of this liquid was weighed into 5 cc. of hot dimethyl formamideuntil the cyclohexane com pound had dissolved. This solution of thesym-tris(4-pi peridyl)cyc1ohexane in DMF was then added to 20 grams ofthe above isocyanate terminated polyetherurethane prepolymer. Instantcrosslinking and gel formation occurred. This example shows that thehydrogenated trimer is a crosslinking or chain extending agent in theproduction of polyurethanes.

EXAMPLE 13 3.33 g. of the sym-tris(4-piperidyl)cyclohexane weredissolved in 30 cc. of DMF and 3.6 g. of phenyl isocyanate were added.The reaction was exothermic and a clear solution was obtained. Afterstanding for one hour the solution was poured into water, the resultingprecipitate was filtered, washed with water and dried at C. under avacuum. The melting point of the vacuum dried product was 105-l07 C.

Analysis for nitrogen (N) showed: percent N: Found, 10.58; calculated,12.19.

This product has the general formula where Ph is phenyl:

The 1,3,5 tris(4 piperidyl)cyclohexanes can be used as curing agents forunsaturated anhydride copolymers such as copolymers of maleic anhydrideand the like and one or more other monomers such as styrene, substitutedstyrenes, vinyl acetate, mixtures of vinyl acetate and vinyl chloride,ethylene, propylene, and vinyl ethers such as methyl vinyl ether andother low molecular weight vinyl ethers as well as the vinyl ethers oflong chain alcohols and mixtures thereof. Methods of making copolymersand the like from maleic anhydride are disclosed in the book Vinyl AndRelated Polymers, Schildknecht, John Wiley and Sons, Inc., New ork,1952. Sufficient minor amounts of the tris(4-piperidyl)cyclohexanes canbe mixed with these unsaturated anhydrides under water free oressentially water free conditions to cure through opening of theanhydride group to form flexible plastic compositions useful for fabriccoatings, moldings and so forth while somewhat larger, although stillminor, amounts can be used to form rigid and semi-rigid products such astote boxes, refrigerator walls and cabinets. Sufiicient times andtemperatures are used to get the desired curing. The copolymers prior tocuring can be compounded with the various fillers known to the art suchas carbon black, SiO T102, glass fibers, stabilizers, color pigments andso forth.

Use of the tris(4-piperdyl) cyclohexanes as telogens in the preparationof polyether and polythioether polyols 'Moreover, the 1,3,5 tris( 4piperidyl)cyclohexanes are of use in the preparation of ethers andpolyether polyols as well as thioethers, polythioether polythiols,polyether polythiols and polythioether polyols. Low molecular weightpolyether polyols are made by reacting 1 mole of the piperidylcyclohexane with from about 3 to 9 moles of an epoxide monomer. Theresulting polyol or triol can then be used to make rigid or semi-rigidpolyether urethanes by further reaction wtih polyisocyanates such astolylene diisocyanate, Papi, hexamethylene diisocyanate, naphthalenediisocyanates, triisocyanates and other polyisocyanates. Addition of H 0or fiuorocarbons, or other blowing agent, and chain extenders ifdesired, silicones, dispersing agents, pigments, etc., can be used inthe polyurethane forming reaction to make foams. If higher mol ratios ofthe epoxide are used such as 15, 30, mols or more per mol of thetris-4-piperidy1 cyclohexane compound, branched long chain polyetherpolyols will be obtained which can subsequently be reacted withpolyisocyanates, etc., to make flexible or rubbery materials or mixedwith foaming ingredients as discussed above to make flexible and/ orrubbery polyetherurethane foams.

The epoxides or organic cyclic oxides which can be reacted with thetris-4-piperidyl cyclohexane compounds can be any epoxide having a ringof 2 carbon atoms and 1 oxygen atom and containing up to a total of 25carbon atoms, preferably not over 12 carbon atoms. The alkenyl, nitro,ether, ester and halogen (except easily ionizable halogen substitutedderivatives) substituted derivatives of these cy clic oxides canlikewise be employed. Mixtures of these epoxides can be used. Examplesof useful cyclic oxides are ethylene oxide (1,2 epoxy ethane), propyleneoxide, 1,2-butene oxide, 2,3-butene oxide, 1,2-dodecane oxide,isobutylene oxide, styrene oxide, epichlorohydrin, 1,2-pentene oxide,isopentene oxide, 1,2-diisobutylene oxide, 1,2- hexene oxide, 2,3-hexeneoxide, 1,2-heptene oxide, allyl glycidyl ether, crotyl glycidyl ether,isoheptene oxide, octene oxide, nonene oxide, decene oxide, hendeceneoxide, methyl glycidyl ether, ethyl glycidyl ether, vinyl cyclohexenemonoxide, phenyl glycidyl ether, 3-methyl-3,4-epoxy butene-l, =butadienemonoxide, glycidyl methacrylate, 2,3- diisobutylene oxide,dicyclopentadiene monoxide, isoprene monoxide, tolyl glycidyl ether,pentadecene oxide, 1,2- epoxy pentacosane, allyl epoxy stearate, andother cyclic oxides.

The epoxides can be reacted with the tris-4-piperidyl cyclohexanecompounds in mass or in a solvent (such as an ether or a hydrocarbon)under conditions which are free of or essentially free of Water, orother material which would adversely affect the polymerization, for aperiod of time and at a temperature sufficient to get the desiredpolymerization or conversion. Temperatures of from about 40 to 250 C.can be used using an alkali metal hydroxide (LiOH ,NaOH, KOH, CsOH,RbOH), preferably KOH, as a catalyst to produce the tris-4-piperidylcyclohexane polyether polyols. Other catalysts may be used which do notreduce the desired hydroxyl functionality. If less than a mole such as/3 mole of the epoxide is used, it will be clear that on the average theresulting material will have only one OH group and two secondary aminogroups. Using /3 mole of epoxide to one mole of the cyclohexane willprovide a diol. If the tris-4-piperidyl cyclohexane compound and theepoxide are in a ratio of 1:3 moles, the average OH functionalityaccording to the kinetics of the alkaline reaction will approach and beclose to 3 or be essentially 3. Using greater than 3 moles of epoxidesuch as to 100 or more per mol of the tris-4-piperidyl cyclohexane willprovide long chain polyether groups terminating on the average in OHgroups and having an OH functionality approaching or being 3. The lengthof the chains on any I one piperidyl nucleus, however, may varydepending on the reaction conditions.

The corresponding sulfur analogs in which a sulfur atom replaces theoxygen atom in the cyclic ether can be used in a similar manner.Examples of such cyclic sulfides are: 4,5-epithio-l-pentene;5,6-epithio-1-hexene; 5,6-epithio-2-hexene; ethylene sulfide;1,2-propylenesulfide; 9,10-epithio-1-decene;7,8epithio-2-methyl-l-octene; 1,2-epithio-1-(Z-cyclopenten-l-yl) ethane;3-allyloxy- 1,2-epithio propane; 3-(2-butenyloxy)-1,2-epithio propane;l,Z-epithio-l-(3-cyclohexen-1-yl)ethane; 3-allylthio-1,2-epithiopropane; 3-(2-butenyl-thio)-1,2-epithio propane, 3-(1-methylallyloxy)-1,2-epithio propane; 3 (l-methyl 2 butenyloxy) 1,2 epithiopropane; 3-(2-cyclohexen-1-yloxy)-l,2-epithio propane; 3-(3-methyl-4-hexenyl0xy)-l,2-epithio propane; 2,3-epithio butane;cyclohexene sulfide; isobutylene sulfide; styrene sulfide; vinylthiirane; 1,2-octene episulfide; crotyl oxy- 1,2-epithio propane;2,3-dimethyl-2-butene sulfide; 3,3 dimethyl thiocyclobutane;thiocyclobutane; allyl thio-1,2-

12' epoxy propane; and other episulfides and mixtures thereof.

Mixtures of the episulfides and epoxides can be used. Moreover, forexample, the 1,3,5-tris(4-piperidyl)cyclohexane can be reacted withseveral mols of an epoxide and then with several mols of an episulfide,or after reacting with several mols of an epoxide, it can be end-cappedat the end of each chain with an episulfide. Likewise, the cyclohexanecan first be reacted with the episulfide and then with the epoxide.Thus, there can be obtained polymers with all ether or sulfide linkages,mixed ether and sulfide linkages, blocks of ether and sulfide linkages,and end groups which have OH and/or SH radicals and which radicals canbe primary, secondary and/or tertiary radicals. These polyols cansubsequently be grafted with vinyl chloride, acrylonitrile, methylmethacrylate using a free radical catalyst.

The resulting 1,3,5-tris (4-piperidyl)cyclohexane poly ether orthioether polymers have the following general formula:

ALL I group of the opened epoxide and/or episulfide ring of 2 carbonatoms and one oxygen and/or sulfur atom of a polymerizable epoxide and/or episulfide having a total of from 2 to 25 carbon atoms, where x iszero or a number, where there is at least one (R'A)H group present, andwhere A is selected from the group consisting of oxygen and sulfur andmixtures thereof. Preferably x is a number of from 5 to 35 to makematerials useful in making flexible polyurethane foams and is a numberof from 1 to 3 in making rigid polyurethane foams. Moreover, (RA) ispreferably Use of the tris(4-pyridyl) and (4-piperidyl)cyclohexanes asaccelerators The 1,3,5-tris(4-pyridyl)cyclohexanes as well as the1,3,5-tris(4piperidyl)cyclohexanes, further, are useful as primary orsecondary accelerators in the curing of the ethylenically unsaturatedpolymeric materials, polymers and copolymers, by means of a sulfur typecuring agent such as sulfur, selenium, tellurium, bis morpholine tetrasulfide, bis benzothiazyl disulfide or tetrasulfide,dipentamethylenethiuram tetrasulfide, selenium diethyldithio-carbamate,selenium dimethyl dithiocarbamate, tetramethyl thiuram disulfide,tetraethyl thiuram disulfide and the like and mixtures thereof.

The polymers and copolymers used can be natural rubber, balata orguttapercha etc. or those made by ionic (Ziegler type) or free radical(peroxide, persulfate, etc.)

catalysts in bulk, solvent, suspension or emulsion systems. Examples ofsynthetic polymers and copolymers which can be used are those obtainedby the polymerization of conjugated dienes such as butadiene-1,3,isoprene, dimethyl butadiene, chloroprene, and other conjugated dienesof from 4 to 8 carbon atoms, alone or in admixture; or teror otherpolymers of one or more of the above conjugated dienes and one or moremonethyleneically unsaturated monomers such as styrene, substitutedstyrenes, acrylonitrile, methacrylonitrile, ethacrylonitrile, methylacrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butylacrylate, octyl acrylate, vinyl pyridine, and the like and mixturesthereof. Graft polymers can also be used. Specific examples are GRS,nitrile rubbers, acrylate rubbers, neoprenes, etc. The monoethylenicallyunsaturated monomers are used in an amount of from to 85% by weight ascompared to the conjugated dienes depending on whether a millablerubbery or a millable thermoplastic curable resinous material isdesired, on whether polymers or copolymers are to be blended together,and on the final products desired, rubber tires, coating, paints,cellular products, tubes, shoe soles, hose, insulated wires, gaskets,automobile body mounts, torsion bars, and so forth. Such polymers andblends thereof are Well known to those skilled in the art.

Still other polymers and copolymers can be used such as butyl rubber, acopolymer of isobutylene and a small amount of isoprene; copolymers ofethylene oxide, propylene oxide, butylene oxide, phenyl glycidyl etherand other aliphatically saturated epoxide monomers with a minor amountby weight of one or more ethylenically unsaturated epoxides such asbutadiene monoxide, vinyl cyclohexene oxide, allyl glycidyl ether,crotyl glycidyl ether and the like. The corresponding episulfidecopolymers can also be used as well as those copolymers obtained bycopolymerizing epoxides and episulfide monomers, i.e., propylene oxideand allyl thioglycidyl ether. Still other ethylenically unsaturatedpolymers can be used such as the condensation polymers, i.e.,ethylenically unsaturated polyesterurethanes, polyetherurethanes,polyetheresterurethanes and the like Where the ethylenic unsaturationmay be in the backbone chain or in a side chain. Yet other polymers canbe used such as the ethylenepropylene polymers containing small amountsof copolymerized dienes conjugated or non-conjugated, althoughpreferably non-conjugated dienes are used such ashexadiene-l,4,norbornene, ethylidene norbornene, dicyclopentadiene,cyclooctadiene. Mixtures of the foregoing polymers and copolymers can beused.

Various compounding ingredients can be used with these millable sulfurvulcanizable ethylenically unsaturated polymeric materials as is wellknown in the rubber and plastic art such as furnace or channel carbonblacks or other blacks, silica, TiO calcium silicates, clay, whiting,color pigments, zinc oxide, stearic acid, zinc stearate, lubricants,Waxes, oils such as extending oils, plasticizers, blowing agents,reodorants, anti-oxidants, anti-degradants, stabilizers, fungicides,other accelerators, and other rubbers and resins, natural and syntheticsuch as styreneacrylom'trile copolymers, acrylonitrile-styrene-butadieneterpolymers, and so forth.

The 1,3,5-tris(4-pyridyl) and (4-piperidyl)cyclohexanes are used in anamount sufficient to accelerate the cure of the polymer and preferablyin an amount of from about 0.2 to 3.7 parts by weight based on 100 partsby weight of the millable sulfur vulcanizable ethylenically unsaturatedpolymeric material. Mixtures of the various cyclohexanes can be used.

The components of the composition are readily mixed together on a 2-rollrubber mill or in a Banbury with the curing agent and acceleratorsusually being added last. The resulting compounded stocks are then curedin molds or autoclaves, depending on the rubber product desired, for aperiod of time and at temperatures (usually about 260 to 345 F.)sufficient to cure or vulcanize the composition to the desired degree.

EXAMPLE 14 Natural rubber compositions were compounded, milled and curedusing the cyclohexanes as primary and secondary accelerators. Thesecompositions were also compared with a compound using a conventionalaccelerator, N- cyclohexyl-2-benzothiazole sulfenamide. The rubbercomposition comprised, all parts being by weight: parts of naturalrubber, 50 parts of fine extrusion furnace carbon black, 5 parts of zincoxide, 2 parts of stearic acid, 3 parts of sulfur and the acceleratorsas shown below. The compounds were molded and cured for 40 minutes at300 F. In the table below are shown the results obtained on testing thecured specimens.

Tensile strength, p.s.1 3, 265 3, 315 3, 390 3, 210 3, 275

Modulus (300%), p.s.i 2, 595 2, 700 2, 530 2, 000 1, 920

Elongation, percent 380 370 410 450 470 Hardness (Shore A) 64 66 68 6160 Monsanto Rheometer Data (300% F.)

Cure rate, percent/1mm 9. 3 8. 3 7. l 2. 9 2. 2

Reversion rate, percent/min 4 3 6 1 0 Scorch time, min 3.0 2. 2 8 1. 81.8

A: N-cyclohexyl-Z-benzothiazolesulfenamide B 1,3,5-tris (4-pyridyl)cyclohexane C: 1,3,5-tris(4-piperidyl)cyclohexane where R is selectedfrom the group consisting of hydrogen and an alkyl radical of from 1 to4 car-bon atoms in admixture with an alkali metal organic imide as acatalyst and a solvent for said pyridine compound, said solvent beingselected from the group consisting of a secondary amine and mixtures ofa secondary amine and another solvent other than said secondary aminewhich does not deactivate the catalyst, which is not proton-active, andwhich does not interfere with nor react with alkali metal or with thealkali metal organic imide, said secondary amine having from 2 to 20carbon atoms and from 1 to 2 secondary amino nitrogen atoms, to form atrimer having the formula where R is selected from the group consistingof hydrogen and alkyl radicals of from 1 to 4 carbon atoms.

2. The method according to claim 1 in which said alkali metal organicimide is formed by the reaction of at least one material selected fromthe group consisting of an alkali metal, an alkali metal amide, analkali metal hydride and an alkali metal hydrocarbon in which thehydrocarbon group has from 1 to 18 carbon atoms and a secondary aminereactive with said material having from 2 to carbon atoms and from 1 to2 secondary amino nitrogen atoms.

3. The method according to claim 2 in which said alkali metal organicimide is formed in situ in the presence of said solvent and prior to theaddition thereto of said vinyl pyridine compound.

4. The method according to claim 2 in which said secondary amine is acyclic secondary amine having the general formula where R is selectedfrom the group consisting of hydrogen and alkyl radicals of from 1 to 4carbon atoms and mixtures thereof, where X is oxygen or sulfur, where mis a number from 2. to 7, where n is 0 or 1, and when X is 1 there arealways at least three CR groups present, two of the CR groups beingattached through the C atom directly to the nitrogen atom.

5. The method according to claim 2 in which said secondary amine isselected from the group consisting of morpholine, piperidine andpyrrolidine and their lower hydrocarbon substituted derivatives.

6. The method which comprises, at a temperature sufficient to causetrimerization, trimerizing a vinyl pyridine compound having the formulawhere R is selected from the group consisting of hydrogen and an alkylradical of from 1 to 4 carbon atoms in admixture with sodium ethyleneimi-de as a catalyst and a solvent for said pyridine compound, saidsolvent being selected from the group consisting of ethylene imine andmixtures of ethylene imine and another solvent other than said ethyleneimine which does not deactivate the catalyst, which is not protonactive, and which does not interfere with nor react with the sodiumethylene imide, to form a trimer having the formula where R is selectedfrom the group consisting of hydrogen and alkyl radicals of from 1 to 4carbon atoms.

7. A method of producing 1,3,5-tris (4-pyridyl)cyclohexane whichcomprises forming an admixture of ethylene imine and sodium ethyleneimide, adding to said admixture 4-vinylpyridine, and maintaining theresultant admixture at a temperature at which said 4-vinylpyridinereacts to form said 1,3,5-tris (4-pyridyl)cyclohexane.

8. A method as claimed in claim 7 wherein the 4-vinylpyridine is addedincrementally.

9. A method as claimed in claim 8 wherein the temperature is maintainedat from about 20 to C.

10. A method as claimed in claim 8 wherein the temperature is maintainedat about 54 C.

References Cited UNITED STATES PATENTS 3,338,907 8/1967 Longi et al26029O JOHN D. RANDOLPH, Primary Examiner A. L. ROTMAN, AssistantExaminer US. Cl. X.R.

260-2, 47, 77.5, 78.5, 79, 79.5, 293.2, 239, 327, 348; 161-184; ll7l32,138.8, 155, 126

323 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,528,988 Dated September 15. 1970 Inventor(s) Heinz Uelzmann It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 3, line 7, "wolud should read would column 3,

line 20, the formula should read Column 3, lines 25-27, "carbon atoms ofthe present invention it is preferred to employ single 4-vinyl pyridinecompounds rather than mixtures." should read carbon atoms and mixturesthereof. In practicing the method of the present invention it ispreferred to employ single t-vinyl pyridine compounds rather thanmixtures. --5 column 3, line 59, 'referred" should read preferred column3, line 65, "(boiling point of the solvent should read (boiling point ofthe solvent) Column line "trimerized-vinyl" should read trimerizedl--vinyl column 4, line 18, "from 1 to carbon atoms" should read from 1to 4 carbon atoms --3 column l, line 29, "l-Q-L-pyridyl," should readl-( r-pyridyl), Column 6, line 4, inhibtor" should read inhibitor Column8 line 2 4-, "l,3,5tris(2,6 dlbutyl-hi erldyl cyclohexane should readl,3,5-tris(2,6 dibutyl-4-piperidyl cyclohexane column 8, line 25, insertl-(fl-piperidyl) column 8, line 25, "3,2 6-dimethyl-4- piperidyl)"should read 3-(2,6 -dimethylk-piperidyl) Column 10, line 1-4, "New ork"should read New York column 10, line 68, "wtih' should read with Column1 4, line 19, 3rd column, "5. should read .5 Column 15, line 30,

o should read H Column 16, line 13, o H,c=c-- should read d A l. H R

Signed and sealed this 30th day of March 1 971 (SEAL) Attest:

EDWARD M.FLETCIER,JR. WILLIAM E. SCHUYLER, JR. Attesting OfficerCommissioner of Patents

